I have always been taught that a 2 blade prop with a longer blade and less pitch is better for speed but gets less thrust . But when it comes to a 3 blade prop you just go with a shorter blade and more pitch . {example} a 18"x8" 2 blade prop is good for a 26cc gas engine but the same engine with a 3 blade would use a 16x10 and still get the same performance and you can see that you would gain two more inches of clearance . Now for me I am trying to find a good quality wood 4 blade that will work good with my 26cc gas KMP P47.
well that's my 2 cents worth .!
hyflyer9.